C＃读取文本文件中列中的每个单词

Question

I've got a problem when I wanted to read and compare each word in my column based text file.

Here is how my file looks like:

[ID]    [Uname] [PW]    [Email]    
0       asd     asd     s   
1       asdd    asd     asd@asd 
2       asd     asd     asd@

I want to read and compare each word in the second column with my textbox's text. If any of them equals with the textbox's text,it would say "The username has taken."

This is the code what i've tried:

string[] lines = File.ReadAllLines(path);
                foreach (var line in lines) { 
                 var firstValue = line.Split(new string[] { "\t" },StringSplitOptions.RemoveEmptyEntries);
                 Console.WriteLine(firstValue); 
                 if (firstValue[1].Equals(txt_uname.Text) && txt_uname.Text != "") {}
    }

The problem is that the "if" checks only the last element(asd) of my [Uname] column

Answer 1

Since you are reading in all the lines at once, this would also work for you.

string[] lines = File.ReadAllLines(path);
if (!String.IsNullOrEmpty(txt_uname.Text) 
     && lines.Where(u => u.Split(new string[] { "\t" }, StringSplitOptions.RemoveEmptyEntries)[1].Equals(txt_uname.Text)).Count() > 0)
{ }

Answer 2

Also it sounds like this is the code you're actually using:

string[] lines = File.ReadAllLines("FilePath");
        foreach (var line in lines)
        {
            var firstValue = line.Split(new[] { "\t" }, StringSplitOptions.RemoveEmptyEntries);
            Console.WriteLine(firstValue[1]); // Needs to have [1] or it will just print System.String[]
        }

Even then, this should work. So we must not be seeing the bigger picture or your file is missing tabs and using spaces as well.

Here's an example of reading the file line by line (more memory proficient in case a file you are consuming could be in the hundreds of megabytes) and then splitting the lines to values to compare with:

using (var streamReader = new StreamReader("FilePath"))
        {
            if (!streamReader.EndOfStream)
            {
                string line = streamReader.ReadLine();

                if (!String.IsNullOrEmpty(line))
                {
                    string[] splitValues = line.Split(new[] { "\t" }, StringSplitOptions.RemoveEmptyEntries);

                    if (splitValues[1] == txt_uname.Text)
                    {
                        // Stuff
                    }
                }
            }
        }